The fire alarm was sounded about 1:15 p.m. A suspicious odor in the Seattle police dispatch center had reportedly made a half-dozen people sick. The caller didn't know what was causing it.

The Hazardous Materials Response Team -- a group of 11 experienced firefighters trained to handle the release of toxic, combustible and chemical agents -- prepared for multiple casualties.

The team, aided by first-arriving Seattle firefighters, are the city's responders for possible terrorist attacks and toxic industrial accidents. Though the city hasn't seen a multicasualty chemical attack, the team that's dispatched about 75 times a year is trained to deal with one.

"When I came in the Fire Department in 1966, we really only did one thing: fight fires," said Assistant Chief A.D. Vickery. "We still came, but we were not really as prepared as we are today.

"We know al-Qaida has pictures of the Space Needle. It's no secret that ferries have been under surveillance. ... But preparedness is a deterrent."

On Nov. 24, eight fire engines, three department aid cars and dozens of officials arrived with the haz-mat team at the dispatch center. Police closed parts of Virginia Street and sections of Eighth and Ninth avenues.

Five haz-mat team members planned to go inside the center or back up those who did. Two set up for possible decontamination. Others were in charge of equipment monitors, safety monitoring, and one stayed in the engine with a computerized resource library to identify a substance.

"They had a certain room they thought the smell came from," said Randy Nye, one of the first two who entered the 911 center. "We asked, 'What do you think it was?' The first thing that comes to mind is usually down the right track."

The firefighters' goal, Vickery said, is to identify a substance within 10 minutes of arrival. Team members huddle for a game plan before entering a building and use initial symptom reports to try to gauge what level of gear they should enter with.

"We have to be really careful when we're talking with people," Nye said. "If we say, 'You may (be) having trouble breathing,' people may start experiencing that."

Unlike the get-in-quick mentality for house fires, haz-mat members say they are meticulous to keep the situation from escalating and to avoid destroying evidence if the incident is criminal.

"In the early days of haz-mat, we went to sites with fences and responsible people with information," Vickery said, adding they still find such situations. "The majority of those were leaks or spills and the risk was relatively low."

The haz-mat team was unveiled in April 1981, after then-Fire Chief Bob Swartout said he wasn't confident with the department's response to chemical leaks a year before. To be a part of the team now, a firefighter must have at least three years experience and pass an interview.

Once selected to the crew, the firefighter has 80 hours of training and continues training during 16 sessions throughout the year.

Housed in an International District station with 56 people rotating in the 11 positions, Seattle's haz-mat crew is among the nation's best. "The only comparable units are in Los Angeles, Chicago and New York," Vickery said.

Many incidents are industrial accidents. But incidents such as the 1995 nerve-gas attack on Tokyo's subway system that killed 12 people and injured 5,000 others have made the department prepare for man-made incidents -- and put people on edge.

Each day in the week after the 2001 anthrax attacks, the Seattle haz-mat team went on about six calls for suspicious white powder and responded to about 300 calls that year, setting a department record. News reports increase their work, raising the 911 calls when a terrorist attack happens somewhere else.

In 2007, firefighters were called to 309 cases involving hazardous materials such as chemical spills, according to department records. The department also responded to 948 calls for hazardous material, including wires and bombs -- 293 more than the previous year.

However, the haz-mat unit responded to about 75 incidents a year because many incidents are handled by neighborhood companies trained for low-level responses, said Capt. Charles Cordova of the haz-mat unit. Multiple casualty response calls, such as the one Monday at the dispatch center, happen about six times each year.

They also help cops with busts of meth labs and have helped in the crackdown of a LSD producer.

Not all cases require the bright yellow suits that enclose firefighters in a vapor-tight garment. Those are reserved for the most hazardous situations.

On Monday, after evaluating the call, the team used the lowest-level response that put firefighters in sealed gloves and other chemical protection equipment in addition to their regular gear. Once inside the dispatch center Monday, Nye and a fellow firefighter used air monitors to check for radioactivity, chemical warfare agents and flammable gasses -- the first step in haz-mat responses. Firefighters then monitored for other chemicals and used the traveling resource library for reference.

As the team worked, three news helicopters hovered overhead and dozens of people gathered around the police line.

"People say 'My God, look at all the equipment out here,' " Vickery said. "But the reality is if there were 100 possible patients that needed decontamination, every piece of that equipment and personnel is needed."

In severe cases, the haz-mat team can do mass decontaminations and shower those exposed. The team can roll in industrial fans for decontamination. On Monday, the three people who had minor symptoms, including watery eyes, improved in the fresh air -- the team's most basic decontamination effort. The only person taken to the hospital had asthma.

Someone suspected pepper spray, but Vickery said air monitors didn't detect that, and they never learned what caused the odor. Earlier this year, the odor that sickened about 20 people at a downtown building was just rotting food.

"The far majority of things turn out to be nothing," said haz-mat firefighter Kevin Dean. "But we have to be prepared."